Because Montana has become a favorite refuge for affluent Californians and Canadians fleeing the effects of policies that they voted for.
https://nbcmontana.com/news/local/montana-comes-in-last-for-home-affordability-in-us
Discussion
Only the bad ones get to flee the consequences of their policies.
The good ones can't take refuge in the U.S. because the covid shots are still required for green cards. Good luck getting an appointed physician to agree any of these are medically inappropriate:
https://travel.state.gov/content/travel/en/us-visas/immigrate/vaccinations.html
Slip the nurse a hundy and ask her to document that she gave you the shot.